What makes someone keep opening an email when they already know it won't change their life? The obvious answer is value — a discount, a useful tip, a timely reminder. But there's a stranger layer underneath: the pull of not knowing exactly what's inside. And that pull gets measurably stronger when the recipient realizes they can't fully predict the reward, yet they can influence it.

The 22% number and where it comes from

Behavioral researchers studying engagement loops have repeatedly found that intermittent, unpredictable rewards hold attention longer than predictable ones. The classic mechanism is variable-ratio reinforcement — the same schedule that makes a slot machine sticky, but also explains why people refresh social feeds and check inboxes compulsively. In email terms, a campaign that occasionally delivers something genuinely surprising (a bonus, a personalized recommendation, a small gift) keeps open rates higher than one that always delivers the same predictable offer.

The 22% figure in the title isn't a universal law. It comes from a pattern observed in A/B tests where one group received a fixed reward every time and another received a reward only sometimes, with the timing and size varying. The variable group showed roughly a fifth longer attention span per message — more time spent reading, more clicks, fewer immediate unsubscribes. The effect is real, but it depends on one condition: the recipient must feel that their own behavior matters.

When the skill gap appears

Here's where it gets interesting. If the reward is purely random — no connection to what the recipient does — attention eventually collapses. People aren't stupid. They learn that opening the email doesn't change anything. The reward becomes noise.

But when the recipient senses that their action (opening, clicking, replying, choosing a preference) actually shifts the odds or changes the reward, the randomness becomes a challenge rather than a lottery. That's the skill gap: the gap between what they can control and what they can't. Too wide, and they disengage. Too narrow, and it's boring. The sweet spot is a gap they can close with effort.

This is the same principle behind decision-making under uncertainty. Kahneman and Tversky showed that people weigh losses more heavily than gains — loss aversion — but they also overestimate their own ability to influence outcomes when they feel involved. In email, that means a subject line like "Your pick: three options inside" outperforms "Surprise inside!" because it hands the recipient a lever.

A concrete example from subscription boxes

Consider a meal-kit company that tested two email sequences. Sequence A promised a fixed recipe every week. Sequence B promised a rotating selection where subscribers could vote on next week's dish. Both had the same discount. Sequence B saw 22% longer average read time and a 14% higher click-through rate over eight weeks. The reward wasn't random — it was variable based on subscriber input. The skill gap was small but real: they could influence the outcome.

What this means for your next campaign

Stop treating unpredictability as a gimmick. Treat it as a design constraint. Ask: does my recipient have a lever? Can they choose the reward, time it, or earn it through a small action? If the answer is no, the randomness will eventually feel like noise.

The forward-looking move is to build feedback loops where the recipient's behavior visibly changes what they get next. Not a points program — those are predictable. A loop where the reward is partly earned, partly unknown. That's where attention lives longest, and where the skill gap stops being a bug and becomes the reason they open.